That is quite possible.
I believe that we will carry 5 WR's plus Slater. Gunner could be the #5 WR. My point in starting this thread is that I don't think that he'll make the roster as a punt returner, without being the #5 receiver.
Edelman, Sanu, Harry, ???, ???, Slater
The other two positions are wide open. Byrd, Meyers and Gunner are the favorites, plus the required UDFA as a competitor (Thomas this year).
And yes, Belichick could trade for a WR, using Sanu's money, or not. IMO, that doesn't affect Gunner.
I think the top 4 are pretty much set with Edelman, Sanu, Harry, Byrd. Damiere will win the deep/burner role by default almost.
The final spot looks like Meyers vs. Gunner and from everything we heard so far it looks like Gunner is decidedly winning that battle.
Unless there are some injuries Meyers will most probably have to hope that we will carry 6 WRs plus Slater.
In summary I think there is a good chance we will indeed only carry 5+1 this year.